Help-A prankster from MyPrankFiles.com has obscured our index page with one of his own

Help! We just set up a new website shell (with no content yet) with the domain name AdFlipster.com and shortly thereafter somebody from MyPrankFiles.com was able to somehow obscure our index page with a page of his own which is clearly not on our server. I have asked them to remove it to no avail.
Any suggestions as to how I can get rid of his crappy page?

P.S. This is not intended in any way to be an attempt to promote our website, especially since we have not begun construction of it and it only has an index page.